Drafting mechanism for textiles



June 12, 1962 R. w. KRAMER ETAL 3,038,213

DRAFTING MECHANISM FOR TEXTILES Filed Nov. 12. 1958 FIG] United States Patent 3,038,213 DRAFTING MECHANISM FOR TEXTILES Rolf Walter Kramer, Stuttgart-Feuerbach, and Kurt Schrotz, Fellbach, Wurttemherg, Germany, assignors to SKF Kugellagerfabriken Gesellschaft mit beschrankter Haftung, Schweinfurt, Germany, a company of Gerany Filed Nov. 12, 1958, Ser. No. 773,459 Claims priority, application Germany Nov. 15, 1957 5 Claims. (Cl. 19250) This invention relates to drafting mechanisms, and more particularly to apron drafting mechanisms, for textiles. The invention is concerned with mechanisms which comprise an upwardly pivotable top roll carrier and loading arm which carries guide arms to be pivotable relative to the plane of the drafting field. The guide arms are provided with loading saddles for receiving twin top rollers. At least one pair of top rollers is engaged by aprons, each of which is passed over an apron cage supported on the journal of the pair of top rollers, and having a rigid guide bar. Each apron is tensioned by a resilient member.

Drafting mechanisms are already known in which top aprons are passed over a front guide member formed as roller, and are tensioned by a cleaning roller pressing from above on the aprons by its own weight. This construction is intended primarily for drafting mechanisms having top rollers which are mounted in end bearings, and cannot be used for centrally mounted top rollers since the space available in the latter case is insufficient for such an arrangement. tions, the guiding, and in particular the lateral guiding, of the aprons is inaccurate, so that accurate running of the aprons during operation is not ensured.

There are also constructions known, in which th ront guide bar for the top aprons is resilient and acts also as tensioning means for the apron. Although this arrangement economizes in space, it has the serious disadvantage that the front apron-guiding edge is not in any fixed position in relation to the axis of the corresponding top rollers, so that displacements of the front gripping point in the drafting field occur, depending on the tension or extensibility of the aprons. However, it is desirable to keep this distance constant since it is of considerable importance to preserve, for each fiber length, the respective spacing of the individual parts of the mechanism in order to ensure the production of a satisfactory and uniform yarn. In addition, the prior construction is complicated and comparatively expensive to manufacture.

The primary object of the present invention is to eliminate the aforesaid disadvantages and to provide an improved drafting mechanism.

Other objects of our invention center about a drafting mechanism which, with a simple and inexpensive construction of the apron cage, ensures accurate guiding and tensioning of the aprons, without variation in the distances of the guide edges from the corresponding axes of the top rollers.

These objects of our invention and such other objects as will be apparent from the following description are achieved, according to the invention, by associating with each apron a resilient tension member which, by a part corresponding in width to the apron, resiliently bears against the latter at a position remote from the drafting field, and is provided with lateral guides for the edges of the apron. By adopting this construction and keeping the guiding edge constant, that is to say, by maintaining a constant distance between the axis of the top rollers and the front guiding edge, variations in the length of the apron are compensated without jeopardizing the satisfactory running of the apron.

In addition, in these construc- The resilient tension members may, in accordance with the invention, take the form of a spring which is adapted to be mounted by securing members either on the apron cage or on its guide bar. The securing members themselves may conveniently comprise complementary and inter-engaging projections and recesses on the top apron cage or the guide bar, on the one hand, and on the resilient members, on the other. For example, protuberances or the like may be formed on the guide bar of the top apron cage and may be adapted to engage corresponding holes in the spring when made of flat material. In the same way, pins connected to the guide bar of the top apron cage may engage holes in the springs.

The springs may surround the guide bar, when viewed relative to the fiber passage through the mechanism, from the front and/or from the rear or from both sides and may be laid or pushed on the bar.

An advantage of the constructions according to the invention is that the apron-guiding edges of the guide bar does not require to be machined if the spring surrounds the guiding edge from the front and thus forms a wear-resistant edge to engage the apron.

To ensure simple and inexpensive manufacture of the springs, the latter are preferably formed in one piece and may consist of flat material, as already mentioned, or may be formed of round material. It will readily be possible to select material of appropriate hardness or resiliency to meet the working conditions.

Tensioning of the aprons may be effected by the spring pressing from the interior against the apron at a position remote from the drafting field. Also, a wire spring may engage the apron from above by means or in form of a resilient stirrup, and may be held on projections on the top apron cage with the aid of co-operating eye portions of the wire, and bent end portions of the wire may lie against the face of the cage. In the latter case, the spring material used will preferably be round material.

The accompanying drawing shows, by way of examples, embodiments of the invention, and in this drawing:

FIG. 1 is a perspective view of a top apron holder, according to the invention, for drafting mechanisms for textiles;

FIG. 2 shows a modified construction in cross-section;

FIG. 3 shows another modification in plan; and

FIG. 4 is a section taken in the plane of the line IV-IV of FIG. 3.-

A top apron cage 1 is formed with saddle-shaped parts 2 to engage in a manner known per se the journal 3 of centrally supported and laterally arranged twin top rollers. The top apron cage 1, together with the twin top rollers, is held by a saddle 24, indicated in FIG. 4, which surrounds the journal 3 between the parts 2 and pivotally carries the assembly so that it can be raised and lowered, from or toward the operative position, in relation to the lower apron. At its front edge, the top apron cage 1 has a part which is bent downwardly and forms a guide bar 5. Placed on the bar 5, for each of the top rollers, is a spring tension member 6 which, with slots 7, engages over pins 8 carried in the guide bar 5 and corresponding in diameter to the width of the slots 7. The member 6 has a curved upper edge to engage the inside of the apron at a position remote from the drafting field, and to ten, sion it. Member 6, furthermore, has laterally bent lugs 9, the inner distance between which corresponds substantially to the width of the top apron 10 indicated in dash-dot lines in the right-hand half of FIG. 1. On their side facing the front guiding edge of the bar 5, the lugs 9 are bent outwardly so as not to impede the running of the apron.

When assembled on the top apron cage 1, the springs 6 assume a position in which the lugs 9 are exactly at right angles to the axis of the top rollers. Since the 3 I lateral lugs 9 are arranged close to the upper edge of springs 6 which bear against the aprons 10, the latter cannot run beyond the lateral guides.

In the embodiment showninFIG. 2, a spring 14 likewise formed from flat material surrounds the guide bar of the top apron cage 1, and is held by pins 8 which engage corresponding holes in the spring 14, thus securing the spring in its position. The spring 14 can be pushed into the bar 5 from the ends of the latter. For the lateral guiding of the top apron 10, bent-up lugs 15 having an outwardly bent edge are provided. As in, or similar to, the constructions shown in FIG. 1, the spring 14 has a circularly formed upper edge which bears from the interior against the top apron and tensions the latter.

In FIGS. 3 and 4, an embodiment of the invention is shown in which a wire spring 16 is provided for tensioning the top apron 10-. The spring 16 surrounds the top apron 10 stirrup-wise from above and is held by eyes 17 on projections 18 on the top apron cage 1. Bent-overend portions 19 of the spring 16 lie against the underface of the top apron cage 1 or the guide bar 5 and thus form a firm support. In this construction, lateral guiding of the apron is provided by parts 16 of the spring 16, which parts 16 run parallel to the apron edge. As Will be seen from FIG. 4, the bar 5 of the top apron cage 1 carries a set screw 20 to engage, in a manner known per se, a guide bar 21 for a bottom apron 22,. partly indicated in the drawing, so that the position of the bar 5 can be adjusted relatively to the pair of rolls 23 and 23'. For loading the guide bar 5, a spring is provided which bears upon the saddle 24 which, in turn, surrounds the journal of the top rollers. The spring 25 engages the top apron cage 1 at the rear, as shown in FIG. 4, but in the constructions shown in FIG. 1, such spring may be secured in recesses 26 in the top apron cage 1.

It will be apparent that although a number of particular embodiments have been described in detail, numerous changes may be efiected without departing from the scope or spirit of the invention. Thus, various modifications regarding the fixing or securing of the resilient tension members to the guide bar or to the top apron cage may be made. There are also various other constructions of the tension members themselves possible which can be adopted while retaining the advantages afiforded by the invention.

We claim:

1. In an apron drafting mechanism for textiles, a support, at least a single pair of spaced top rollers mounted on said support for rotation about an axis, an apron cage mounted on the support between said rollers and including an elongated guide bar longitudinally extending in a direction substantially parallel to said axis, two endless drafting aprons, each of said aprons trained over one of the top rollers and the guide bar, two resilient tensioning members separately secured to said guide bar, each tensioning member having an elongated portion resiliently bearing from the outside against and independently of the other tensioning member, tensioning the respective apron, the tensioning members being formed as springs, the springs being substantially coextensive with the aprons in said direction.

2. In the mechanism according to claim 1, the tensioning members being formed from spring wire.

3. In the mechanism according to claim 2, each ten- Sioning member being formed to constitute guiding means for lateral guiding contact of the respective apron.

4. In the mechanism according to claim 2, each tensioning member being substantially stirrup-shaped and including two end portions secured to the guide bar, and a central portion constituting said elongated portion.

5. In the mechanism according to claim 4, the guide bar being provided with two pairs of opposite projections, each two end portions being formed as a pair of eyes to releasably engage the respective pair of proectlons.

References Cited in the file of this patent UNITED STATES PATENTS 2,708,290 Karl-Hans Neu et al. May 17, 1955 FOREIGN PATENTS 552,764 Belgium Dec. 15, 1956 911,225 Germany May 10, 1954 14,228 Great Britain of 1915 

